Year	Percent
1978-12-31	12.565
1979-12-31	17.065
1980-12-31	14.875
1981-12-31	15.75
1982-12-31	10.5
1983-12-31	9.375
1984-12-31	10.03
1985-12-31	11.91
1986-12-31	11.22
1987-12-31	8.925
1988-12-31	13.205
1989-12-31	15.145
1990-12-31	14.03
1991-12-31	10.94
1992-12-31	7
1993-12-31	5.31
1994-12-31	6.545
1995-12-31	6.485
1996-12-31	6.455
1997-12-31	7.545
1998-12-31	6.175
1999-12-31	5.9688
2000-12-31	5.8282
2001-12-31	4.0469
2002-12-31	3.95
2003-12-31	3.965
2004-12-31	4.825
2005-12-31	4.58
2006-12-31	5.275
2007-12-31	5.95
2008-12-31	2.825
2009-12-31	0.625
2010-12-31	0.775
2011-12-31	1.1
2012-12-31	0.5
2013-12-31	0.53
2014-12-31	0.53
2015-12-31	0.57
2016-12-31	0.37